Self-tightening snow chains have been used to provide vehicles with improved traction when driving on irregular surfaces where poorer traction is anticipated (i.e., ice or snow covered surfaces, off-road or backcountry terrains). Numerous states require the use of snow chain under certain weather conditions to mitigate potential hazards. Some models of snow chains require retightening after initial chain installation, where all of the wheel chains need to be retightened after the vehicle has been slowly driven forward or backward. It is essential that snow chains fit properly to obtain proper performance and increase durability. Having to retighten the cables is burdensome for the user and has costly consequences if forgotten or neglected.
Because proper fit of the snow chains is so essential, self-tightening snow chains have been developed. One of these devices is disclosed in U.S. Pat. No. 6,213,421 to Franklin. The Franklin patent discloses a clamping lock for a traction device. The lock has a single clamping rope connected to a winding device within a housing. The winding device is pre-tensioned in the wind-up direction. Toothing is provided laterally around the winding device. There is an actuating lever attached to the housing that has three positions: a first catch position, which allows the clamping rope to move in or out of the housing; a second wind-up position, which unlocks the rope so it may move into the housing, thereby tightening the clamping rope; and a third locked position wherein the clamping rope is locked in its current position. The lever controls a pawl. Whether or not the clamping rope may be pulled in or out of the housing depends on whether the pawl is engaged with the teeth on the winding device.
Self-tightening snow chains having tensioning devices of this kind are difficult to secure to a wheel of a vehicle with two hands. A user may need to let go of the cord in order to better grip the tensioning device or grab the corresponding hook on the snow chain. In order to prevent the cord from being pulled back into the housing, the user must lock the cord in both directions to keep the cord in the extended position. Then, the cord would need to be unlocked to extend further, again requiring releasing either the cord or the corresponding hook. Additionally, self-tightening snow chain tensioning devices that can only tighten one cord are less cost effective because numerous self-tightening tensioning devices are required on each snow chain to tighten each cord.
Of further concern, self-tightening snow chain tensioning devices of this kind are made by simply screwing two flat-edged housing pieces together. Dirt, debris and moisture may easily penetrate this type of joint and cause damage to the mechanisms inside the housing. Additionally, the use of actuating levers creates an easy path for dirt, debris and moisture to enter and damage the device. It is also noted that the tensioning cord is generally equipped with crimped on or cast on ends and that one of these ends is then passed through a grommet and that the grommet and the cord are then incorporated into the tensioning device during assembly. In order to accept the crimped or cast on end, the opening in the grommet is required to be quite a bit larger than the diameter of the cord and the difference in size provides another area where an easy path is provided for dirt, debris and moisture to enter and damage the device.